Seems to me that the rub "manufacturers" can't win. Some rubs get criticized for being all salt, others not salty enough. I've blended my own rubs and had some great results, but if my ingredients would have been 3 years old the results would have been different. Ground spices clearly have a shelf life, especially after the vacuum seal is broken.
Here's my best advice; figure out what your goals are. (1) good enough for you/your friends/family or (2) competition/blowing people away. Then, plan accordingly. If cooking for friends and family, special occasion, get a brand new bottle of vac sealed rub from Kosmo, or Killer Hogs or Blues Hog, and go for it. Don't use 3 year old paprika/cumin/cayenne/garlic powder from your pantry and expect "great results".
If your goal is competition/blowing people away, you'll need the freshest spices, and also fresh smoke wood. You'll have to use it up, or unfortunately pitch spices and smoke wood as they go "stale". IMHO - doubling up on stale spices or smoke wood doesn't produce the same quality as having "fresh"
All this being said, Kosmo's Dirty Bird is the best/most "complete" rub i"ve used yet on pork and chicken. Killer Hogs Rub is also good, but as EricV said, you need a base layer of something salty to make it work. Killer Hogs SPG is recommended, but I've used Tony Chachere's, Lowry's and plain old salt pepper and garlic. For brisket, or beef ribs, course kosher salt, and a fresh bottle of McCormick's course ground black pepper works real nice.
